Charge forming method and apparatus



Nov. 27, 1962 B. c. PHILLIPS 3,065,957

CHARGE FORMING METHOD AND APPARATUS Filed June 24, 1960 5 Sheets-SheetIl 1n 44 4l E. 46 46 34 4 f/q I I I a 47 if s/ I f .5 26 z 32 455/50'1-1@(24. T-

ATTY.

Nov. 27, 1962 B. c. PHILLIPS 3,065,957-

CHARGE FORMING METHOD AND APPARATUS Filed June 24, 1960 l 5 Sheets-SheetA2.

BERNARD E PHILLIPS.

BY Agip?? NOV. 27, 1962 B, C, PHlLLlPs 3,065,957

v CHARGE FORMING METHOD AND APPARATUS Filed June 24, 1960 5 Sheets-Sheet3 lNVENTOR: .BEHNAHU DPHILLIPS Way @e5/JW ATTORNEY.

United States YPatent O M' 3,065,957 CHARGE FORMING METHOD AND APPARATUSBernard C. Phillips, Toledo, Ohio, assigner to The TillotsonManufacturing Company, Toledo, Ohio, a corporan tion of Ohio Filed June24, 1960, Ser. No. 38,534 Claims. (Cl. 261-35) This invention relates toa method of forming a combustible fuel and air mixture or charge for aninternal combustion engine and charge forming apparatus and moreparticularly to a charge forming apparatus embodying a diaphragmcontrolled fuel metering means for regulating delivery of fuel from asupply into a diaphragm chamber and wherein fuel is delivered from thediaphragm chamber into an air and fuel mixing passage solely byaspiration or differential pressure established by air flow through themixing passage.

Diaphragm type carburetors have been used for supplying combustiblemixture particularly for engines of the two cycle type utilized forpowering chain saws, lawnmowers, outboard motors and the like where fueleconomy under comparatively light load conditions is not of primaryimportance and where large capacity carburetors have not been required.

In carburetors of the diaphragm type wherein the fuel delivery into themixing passage is effected solely by aspiration or reduced pressure in amixing passage acting upon an unvented fuel chamber of Variable volumethrough the provision of a diaphragm forming a wall of the chamber orreservoir, there is a marked tendency for the delivery into the mixingpassage under comparatively light load conditions of more fuel than isrequired to maintain a normal fuel and air mixture ratio supplied to theengine. In engines, particularly those of larger size, it is desirableto supply a lean mixture at light loads for improved economy, and tosupply a richer full-power mixture near full power loads. Furthermore itis desirable to provide for the momentary delivery of additional fuel tothe mixing passage for engine accelerating purposes where the carburetoror charge forming device is utilized with engines adapted to operateunder varying load conditions.

The present invention embraces a method of forming fuel and air mixturecharges for an internal combustion engine providing for a reduction offuel delivered into the mixing passage when the engine is operatingunder partial open throttle or light load conditions so as to renderengine operation more economical without impairing the power of theengine under such operating conditions.

An object of the invention is the provision of a charge formingapparatus of the diaphragm type embodying a pressure responsive meansfor effecting the reduction in the amount of fuel delivered into an airand fuel mixing passage when the engine with which the charge formingapparatus is used is operating under light loads above the normal idlingspeed of the engine.

Another object of the invention is the provision of a method of andcharge forming apparatus for leaning out of the fuel constituent of thecombustible mixture under engine operating conditions where maximumpower is not required.

Another object of the invention is the provision of a charge formingapparatus of the Idiaphragm type which may be fashioned for use withboth two cycle and four 1,

cycle engines of various sizes and improve the efficiency and economy ofoperation of the engines.

Another object of the invention resides in a carburetor of the diaphragmtype wherein fuel is delivered into the mixing passage solely byaspiration from an unvented 3,065,957 Patented Nov. 27, 1952 fuelchamber embodying primary and secondary fuel delivery systems, thearrangement providing means for the momentary delivery of fuel into themixing passage for engine accelerating purposes and embodying a pressurecontrolled means for admitting air into the fuel prior to its deliverythrough the primary system into the mixing passage under certainoperating conditions.

Another object of the invention resides in a diaphragm type carburetorwherein fuel delivery into the mixing passage is solely under theinfluence of aspiration or reduced pressure in the mixing passage, thecarburetor embodying a secondary diaphragm as an assist in fostering oraccelerating the momentary delivery of additional fuel into the mixingpassage for engine accelerating purposes when an enriched mixture isrequired for rapid increase in engine speed.

Another object of the invention resides in a diaphragm type carburetorembodying a manually operable choke or air control valve mounted forautomatic opening, the extent of opening of the choke valve beingdependent upon and responsive to the velocity of air ow through themixing passage.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements per se, and to economies of manufactureand numerous other features as will be apparent from a consideration ofthe specification and drawing of a form of the invention, which may bepreferred, in which:

FIGURE l is a side elevational view of a charge forming apparatus orcarburetor of the invention;

FIGURE 2 is a top plan view of the carburetor or charge formingapparatus illustrated in FIGURE 1;

FIGURE 3 is a view from the end of the carburetor which is adapted to belattached to an engine crankcase or intake manifold;

FIGURE 4 is a view of the opposite end of the carburetor;

FIGURE 5 is an enlarged longitudinal sectional View through thecarburetor, the View being taken substantially on the line 5-5 of FIGURE2;

FIGURE 6 is an enlarged transverse sectional view taken substantially onthe line 6 6 of FIGURE 2;

FIGURE 7 is a detail sectional view taken substantially on the line 7--7of FIGURE l;

FIGURE 8 is a detail sectional view taken substantially on the line 8--8of FIGURE 1;

FIGURE 9 is a detail sectional view taken substantially on the line 9 9of FIGURE 2;

FIGURE l0 is a sectional view taken substantially on the line lil-lll ofFIGURE 2;

FIGURE l1 is a detail sectional view taken substantially on the line11-11 of FIGURE l0, and

FIGURE l2 is a semi-diagrammatic view illustrating the association `andoperation of components of the carburetor of the invention.

While the method of forming combustible mixture for use with an internalcombustion engine and the charge forming apparatus of the invention areusable with both two cycle and four cycle engines, the invention hasparticular utility in use with engines where rapid engine accelerationis imperative yet economical operation desired under light loadconditions of the engine.

Referring to the drawings in detail, the charge forming apparatus orcarburetor for carrying out the method of the invention is inclusive ofa carburetor body or body member lil preferably formed of die cast metalor of molded plastic or resin which is resistant to deterioration byhydrocarbon fuels. The body member 10 is formed with a fuel and airmixing passage 12 in which liquid fuel and air are mixed or commingledto provide a combustible mixture for delivery to an internal combustionengine with which the carburetor may be used.

The mixing passage includes an air inlet or inlet region 14, a venturihaving a choke band or restricted portion or region 16 and a mixtureoutlet 17. The outlet end of the mixing passage is adapted to registerwith an inlet port inthe crankcase of a two cycle engine or, where thecarburetor is employedy with a four cycle engine, the outlet end is inregistration with an intake manifold arrangedto convey combustiblemixture to the cylinders of the engine. The body 10, adjacent the outletend of the mixing passage is provided with a mounting flange 18 formedwith openings 19 adapted to receive bolts (not shown) for securing thevmounting flange to an engine crankcase or to an intake manifold.

A choke valve arrangement of novel construction is provided at the airinlet region 14 of the carburetor mixing passage for regulating orcontrolling the admission of air into thetmixing passage which isadaptable for semiautomatic operation in that its relative position isiniluenced by the magnitude of velocity of air entering the air inletregion 14. With particular reference to FIGURE 10, it will be seen 'thatthe carburetor body 10 is fashioned with transversely aligned bossportions .21 and-22, the boss Vportion 21 having a bore accommodating abearing or sleeve 23, the outer end of the bore accommodating thesleeve-23 being closed by a plug or cap 24.

The boss 22 is provided with a bore adapted to receive a'bearing orbearing sleeve 25, the bearings 23 and 25 being pressed into the alignedbores. Rotatably mounted in the bearings 23 and 25 is a shaft 26provided with a slot accommodating a thin disc-like choke valve 28 forthe air inlet region 14, the valve disk 28 being secured to the shaft bya screw 29.

As shown in FIGURE l0, the axis of the shaft 26 is disposed above oreccentric with respect to the axis of the mixing passage inlet region 14whereby a major area of the valve disk 28 is at one side of the axis ofthe shaft 26.

The bearing 25 in the boss 22 is provided with an extension or sleeveportion 32 of slightly larger diameter than that of the bearingportion'25. Mounted for rotation upon the sleeve portion 32 is agenerally cylindrically shaped member 34 fashioned witha radiallyextending arm 35 having an opening at its distal end in which isjournaled a cylindrically shaped connector 37 as shown in FIGURE 2. Thefitting 37 is formed with an opening 3S to receive the extremity of amanipulating rod or bowden wire (not shown) which is secured in theopening 38 by a setscrew 40.

By manipulation of the wire or cable connected with the fitting 37, themember 34 may be rotated about the bearing provided by the sleeveextension 32. As particularly shown in FIGURE l0, the member 34 isformed with a cylindrical chamber 41. The shaft 26 is provided with atransverse opening in which is snugly fitted a pin 43. The member 34 isprovided with an abutment in the form of a pin 44 whereby rotation ofthe member 34 in one direction engages the abutment 44 with the `pin 43so as to elect positive manual rotation of the choke valve shaft 26 insaid one direction. The sleeve extension 32 is provided at its outer endwith a flange 45 disposed in a counterbore in the member 34 to preventendwise movement of the member 34.

VThe outer end region ofthe member 34 is provided with a circular recessaccommodating a circular disk-like plate or closure member 47 having anopening to receive a tenon portion 48 of a pin 49 which projects intothe chamber 41. Surrounding the portion of the shaft 26 within thechamber 41 is a coilspring 50, one end 51 of the spring being hooked onthe pin 43, the other end of the spring being engaged with the pin 49 asshown in FIGURE l0.

Through the resilient connection provided by the spring 4 50 between thepin 49 mounted by the member 34 and the choke valve shaft 26, the chokevalve is resiliently biased against movement in the opposite directionby means of the spring 50. As the choke valve 28 is off center oreccentric with respect to the axis of the air inlet region 14 of themixing passage, air flowing past the choke valve 28 tends to open thevalve against the resilient bias of the spring 50.

Thus when the choke valve is manually moved to a closed position byrotating the cylindrical member 34 and the engine is started, theunbalanced condition of the choke valve 28 will admit air flow past thechoke valve against the resilient bias of the spring 50 even though themember 34 has not been fully rotated to a position to permit fullopening of the choke valve viz. the position of the choke valveillustrated in FIGURES 4 and 10.

However through the abutting connection of the pin 44 with the pin 43,movement or rotation of the member 34 in a direction to open the chokevalve 28 will eifect a positive opening movement of the choke valve tothe position shown in FIGURES 4 and l0.

The plate 47 supporting the pin 48 is secured in position by means ofscrews 46 threaded into suitable bosses formed on the substantiallycylindrically shaped portion 34 the heads of the screws overlapping theperipheral region of plate 47. By loosening the screws the circularplate'47 may be adjusted to vary the biasing force of the .spring 50.

The mixture outlet region 17 of the mixing passage is provided with adisk-type throttle valve 54 which -is mounted in a slot formed in athrottle shaft 56 and held in place by a screw 57 threaded into a borein the shaft 56. The shaft 56 is journaled in suitable bores formed inthe body of the carburetor and in a boss 5S. A portion of the throttleshaft extends exteriorly of the boss 58 and is provided with an arm 60equipped with a fitting 61 adapted to receive a Bowden wire controlmeans (not shown) or other suitable means for manipulating the throttlevalve shaft 56.

The arm is held to the shaft by swaging a portion-62 of the shaft intosnug engagement with the arm 60. As shown in FIGURE 3, the carburetorbody 10 is provided with a projection 64 accommodating an adjustingscrew 65 adapted for engagement with a projection 67 fashioned on thearm 60 to limit the movement of the valve toward closed position, thevalve being adjusted slightly open to accommodate the ow of a smallamount of air through the mixing passage for admixing with the fuelsupplied to the mixing passage for engine idling purposes.

As particularly shown in FIGURES 5 through 8, the carburetor body 10 isformed with a generally circular recess close to the mixing passageproviding a relatively shallow fuel chamber 68 defined by an annularflange portion 69 of the carburetor body. A highly exible membrane ordiaphragm 70 formed of impervious material which is resistant todeterioration by hydrocarbon fuels extends across the shallow fuelchamber 68 and forms a flexible wall-of the chamber.

Disposed between the circular peripheral region of the diaphragm 70 andthe annular portion 69 is an annular sealing gasket 71 providing a Huidtight seal between the periphery of the diaphragm and the annularportion 69. A circular disk-like member 73 engages the oppositeperipheral edge region of the diaphragm 70. The central region of themember 73 adjacent the diaphragm '70 is formed with a cone shapedrecesss or chamber 75 defined by the surface 76 and the opposite centralregion of the member 73 is formed with a conically shaped surface 76which denesva chamber or recess 77.

Extending across the recess or chamber 77 is a second diaphragmormembrane 80 formed of highly flexible impervious material, which incooperation with the diaphragm 70, provides an impulse arrangement undercerl tain operating conditions for engine accelerating purposes ashereinafter described. Disposed at the opposite side of the seconddiaphragm 80 is a circular closure plate 82 having a peripheral boss orange portion S3 which engages the peripheral region of the seconddiaphragm Si? as shown in FIGURES 5 and 6.

The circular boss portion 83 is provided with a plurality ofcircumferentially spaced openings and the disklike member 73 formed withopenings aligned therewith to accommodate securing screws 85 threadedinto openings formed in the circular boss portion 60 of the carburetorbody for securing the diaphragms 74?,l Si?, the disk-like member 73 andthe closure plate S2 in assembled relation, as shown in FIGURES 5 and 6.The boss portion 83 of the closure member 82 defines a circular chamber87 formed with a depen-ding centrally disposed boss portion 88.

The boss portion 88 is formed With a socket or recess 89, the bottom ofthe recess being defined by a partition 90 beneath which is a bore 91and a counterbore, a fine mesh screen or filter 93 being disposed in thecounterbore in the boss portion 80 as shown in FIGURE 6. The partition90 is provided with a minute or very small vent passage 95. An expansivecoil spring 97 is arranged in the socket 89, the spring being arrangedto exert an upward bias or force upon the diaphragm 86.

The diaphragm 80 is provided with a circular reinforcing disk 99preferably formed of sheet metal which is engaged by the spring 97, thespring being centered with respect to the diaphragm S0 by means of a pin169, the upper end of which is swaged into engagement with a washer 101for securing the reinforcing disk 99 to the diaphragm Si). As shown inFIGURE 5, an orifice 1114 is formed in a wall of the outlet region 17 ofthe .mixing passage, the orifice being the outlet of a channel 1116which extends through a portion of the carburetor body 111, the sealinggasket 71, diaphragm 70, member '73, diaphragm 80 and partially into theclosure member 82.

The closure member 82 is provided wtih a boss portion 108 in which isformed an angularly disposed passage 110 in communication with thechannel 166 whereby under certain operating conditions of the engine theaspiration in the mixing passage is communicated to the chamber S7. Thefirst diaphragm 70- provides a component of means for controlling orregulating the iiow of liquid fuel into the chamber 68 from a fuelsupply in accordance with the rate of delivery of fuel into the mixingpassage 12. The fuel chamber 63 is unvented to the atmosphere and isactuated or flexed solely by aspiration or reduced pressure Set up inthe mixing passage 12.

The aspiration, suction or reduced pressure in the chamber 68 iseffective to cause delivery of fuel through fuel delivery passages andnozzles or outlets hereinafter described opening into the mixing passage12. The diaphragm 80 is actuated by impulse pressure set up orestablished in the chamber 87 under certain operating conditions ashereinafter explained.

The chamber '7S between the diaphragms 711 and 8th in the member 73 ispreferably vented to the inlet region 14 of the carburetor body as theair inlet region is preferably provided with a filter (not shown)secured to a fiange or boss portion 112 having threaded openings 114 toaccommodate securing bolts (not shown) for retaining an air filter inposition. As shown in FIGURE 5, an air entrance tube 118 pressed into abore in the wall of the body 10 defining the air inlet region 14 and isin communication with the passage 121i which extends partially into themember 73.

'Ihe interior portion of member 73 is provided with a notch or recess122 which is in communication with the passage 120 by a restrictedchannel or duct 124 which is of small size to restrict or retard airflow out of the chamber 75 when the diaphragm S41 is rapidly movedupward under the inuence of the spring 97.

As shown in FIGURES 5 and 6, an elongated recess 128 formed in the wallregion of the carburetor body de-A iining the shallow fuel chamber 68accommodates a lever 130 formed of sheet metal, the lever 131) beingprovided intermediate its ends with a loop portion accommodating a pin132 forming the fulcrum for the lever 130. The pin 132 is provided witha threaded portion 133, shown in FIGURE 4, threaded into a bore in thecarburetor body facilitating assembly of the pin 132 and lever 13th inthe body.

Disposed at opposite sides of the first diaphragm 70 are metal disks orreinforcing members 135 and 136, a member or rivet 137 extending throughopenings in the disks and diaphragm. The head portion of the rivet 137is engaged by the long arm of the lever 130 at the right side of thelever fulcrum 132 as viewed in FIGURE 6. An expansive coil spring 139 isdisposed in a recess formed in the carburetor body and engages the armof the lever at the right side of the fulcrum 132 as viewed in FIGURE 6,normally biasing the lever 130 into engagement With the rivet 137 sothat movement of the diaphragm 70 effects pivotal movement of the lever130 about its fulcrum.

The short arm 14@ of the lever is adapted to engage an end of a fuelinlet valve member or valve body 142. The carburetor body 1t) is formedwith a threaded bore to receive a valve cage or valve guide fitting 144,the fitting being fashioned with a central bore in which a valve member142 is slidably accommodated. The valve body or member 142 is preferablyof polygonal cross-section, for example, rectangular cross-section, tofacilitate flow of liquid fuel along the facets provided by thepolygonal cr0sssection.

Arranged in a counterbore at the upper end of the fitting 144 is anannular valve seat 146 preferably formed of yieldable or semi-hardmaterial such as neoprene or other suitable material which is resistantto deterioration by hydrocarbon fuels. The annular valve seat 146provides a fuel inlet port 147. A sealing gasket 148 is disposed betweenthe upper end of the fitting 96 and the ledge formed at the end ofthebore in the body accommodating the fitting 144.

The valve member 142 is formed with a cone-shaped valve portion 150extending into the port 147 and cooperating with the valve seat 146 tometer, regulate or control the flow of fluid fuel from a supply into thediaphragm chamber or a fuel reservoir 63. The carburetor body 10 isformed with a boss portion 152 provided with a threaded bore 153accommodating a threaded fitting (not shown) adapted to be connectedwith a fuel tank, a fuel pump or other source or supply of liquidhydrocarbon fuel. A fuel strainer or screen 154 is preferably disposedin the threaded bore 153.

The port 147 in the Valve seat is in communication with the threadedbore 153 through connecting passageways 155 and 156. The fuel supply forthe carburetor may be by gravity flow directly from a tank or receptaclepositioned or located above the carburetor, or the fuel supply may befrom a fuel pump connected with a fuel tank. The port 147 provided inthe annular valve seat 146 is preferably of comparatively small diameterin orderto present a minimum area of the coneashaped valve portion 150to the pressure of the incoming fuel in order to render the fuel controlmeans responsive to minute pressure variations in the chamber 68.

The carburetor body is fashioned With ducts, channels or passages formedor drilled therein for conveying fuel from the fuel chamber 68 into themixing passage 12. As shown in FIGURES 5 and 7, the region of thecarburetor body adjacent the choke band 16 of the venturi 15 is bored toaccommodate a tubular fitting providing a main orifice or primary fueldischarge opening 162 at the choke band 16 of the venturi. DisposedWithin the uppe portion of the tubular member 160 is a valve means inthe form of a ball valve or check ball 164.

The lower portion of the tubular member 160 is provided with a tenonportion 165 of reduced diameter provided with a passage or bore 166 oflesser diameter than that of the check ball 164 and which is adapted tobe closed by the check ball under certain conditions of operation ashereinafter explained.

A perforated member 168 preferably of sheet metal is disposed in thetubular fitting 160 above the ball check valve 164 to preventdislodgment of the valve member 164 from the chamber in the tubularmember 160. The member 168 permits the delivery of fuel through the mainnozzle 162 into the mixing passage.

The hollow tenori portion 165 of fitting 160 extends into a well or duct170, the lower end of which is closed by a Welsh plug 172. The Well 170is of a size to accommodate a small amount of reservoir of fuel foraccelerating purposes. Formed in a boss portion 174, shown in FIGURE 7,is a bore 175 which terminates adjacent the well 170 in a threadedcounterbore of lesser diameter, the outer end of the bore 175 beingclosed by a threaded plug 176. Disposed in the bore 175 is a fitting 177having a threaded portion 178 extending into the threaded counterbore.

The fitting 177 is provided with a restricted fuel metering passage 180for metering or restricting fuel liow into the well 170. The bore 175 isin communication with the diaphragm fuel chamber 68 by a passage or duct182, shown in FIGURE 7, whereby fuel from the diaphragm chamber 170flows through passage 182, bore 175 and restricted metering passage 180into the well 170 for delivery through the passage 166 past the checkball 164 into the mixing passage through the main orifice 162.

The embodiment of the invention illustrated embodies a secondary fueldelivery system for delivering fuel into the mixing passage for engineidling and low speed purposes. As shown in FIGURE 5, the carburetor bodyis formed with a bore 184, the end of the bore adjacent the fuel chamber68 being closed by a plug 185. The bore 184 is in communication with thewell 170 by means of a duct or channel 186. It should be noted that thepoint of entrance of channel 186 into the well 170 is at the upper endof the.well, the channel 186 supplying fuel from the well to thesecondary fuel delivery or orifice system.

As shown in FIGURE 8, the carburetor body is formed with a supplementalchamber or bore 187, the exterior region of which is closed by a Welshplug 188. The secondary orifice system includes an orifice 190 forengine idling purposes and a second orifice 192 for supplying fuel forlow engine speeds. These orifices are illustrated in FIGURE l2 and inbroken lines in FIGURE l and are in communication with a supplementalchamber 187 from which fuel is delivered through the orifices into themixing passage under certain engine operating conditions.

The engine idling orifice 196 is disposed slightly forwardly of a nearlyclosed position of the throttle valve at the engine side of thethrottle, while the low speed orifice 192 is at the opposite side of thethrottle valve when the latter is in substantially closed position. Asshown in FIGURE 8, the body 18 of the carburetor is provided with a bossportion 194 provided with a threaded bore to receive the threadedportion 196 of a manually adjustable valve body 198.

The threaded portion 196 is provided with a tenori 206 of reduceddiameter which is of lesser diameter than the bore 262 whichaccommodates the tenon 200, the tenori terminating in a tapered needlevalve portion 284 which extends into a restricted passage 206 which isin cornmunication with the bores 184and 202. A sealing gasket 288 isdisposed in a counterbore formed in the boss 194 and an expansive coilspring 210 is disposed between the sealing gasket 288 and a knurled head212 formed on the valve `body 198 providing a finger grip means foradjusting or manipulating the valve body 198.

The bore 262 is in communication with the supplemental chamber 187 bymeans of an angularly arranged channel or duct 214, It will be apparentfrom the forea going that the fuel for delivery through the secondaryorifice system viz. the orifices 190 and 192, fiows through the duct186, bore 184 through the restricted passage 286, bore 282, channel 214and secondary or supplemental chamber 187 thence through one or both ofthe orifices 199 and 192 into the mixing passage 12 depending upon therelative position of the throttle valve 54.

By rotating the valve body 198, the needle valve portion 264 may beadjusted to regulate or meter fuel flow to the secondary orifice systemfrom the bore 184. The arrangement is inclusive of means for admitting asmall amount of air into the upper end of the accelerating well 179 forbleeding air into the fuel for delivery from the main or primary orifice162 when the engine is operating at intermediate or high speeds. Asshown in Figure 5, a cup-like `fitting 218 is provided in a borearranged between the air inlet region 14 and the accelerating well orchamber 17) as shown in FIGURE 5.

The fitting 218 is provided with a small aperture or passage 229 toadmit a restricted amount of air from the air inlet region 14 into thewell 170 for admixing with the fuel for delivery through the mainorifice 162 when the fuel in the accelerating well is exhausted orsubstantially exhausted through the main orifice 162.

The embodiment of the present invention is inclusive of a method andarrangement for admitting or introducing additional air for admixingwith the fuel in the well for delivery from the main orifice when theengine is operating under light load or constant speed conditions wherefull power is not required. The arrangement includes means forautomatically modifying or varying the fuel and air ratio by pressuredifferentials in the mixing passage. Such means comes into operationautomatically to lean the mixture by bleeding additional air into thefuel when the engine is operating under light loads above the normalidling speed of the engine whereby a substantial increase in the economyof operation is effected.

With reference to FIGURE 9, the carburetor body 10 is formed with acylindrically shaped boss portion 224 provided with a bore, cylinder orchamber 226 terminating in a counterbore 228 of lesser diameter.Slidably mounted in the cylinder 226 is a piston-type valve 238 formedwith a recess accommodating an expansive coil spring 232, one end of thespring extending into the counterbore 228, the bottom of the counterboreforming an abutment for the spring. The end of the bore or cylinder 226adjacent the piston valve is closed by a threaded plug 234.

The wall region of the cylinder 226 adjacent the inner end of thethreaded plug 232 is in communication with the air inlet region 14 ofthe mixing passage by means of a channel or passage 236. The body 10 isformed with a boss portion 238, as shown in FIGURES l and 9, withinwhich is a drilled channel 240 opening into the cylinder 226, the outerend of the channel 240 being closed by a cap or plug 241.

The lower end of the channel 240 is in communication with a passage orchannel 242 shown in FIGURES 6 and 9, the outer end of the drilledchannel 242 being closed by means of a cap 243 the channel 4or bore 242is in communication with the channel 186, which supplies fuel to thesecondary orifices, through a restricted passage or air metering channel245 shown in FIGURE 6. The small diameter counterbore 228 formed at theend of the cylinder or bore 226, shown in FIGURE 9, is connected with apassage 248 in the carburetor body by means of a channel or passage 250.

A passage 252, shown in broken lines in FIGURES 1 and 9, connects thepassage 248 with the mixing passage, the outlet or orifice 254 into themixing passage being illustrated in broken lines in FIGURES l and 9. Inthis manner the bore or cylinder 226 at the left end of the slidablepiston 230, as viewed in FIGURE 9, is under the inluence of pressuredifferentials existent in the outlet region of the mixing passageadjacent the throttle valve.

When the suction or aspiration in the outlet region 117 of the mixingpassage is sufficient to move the slidable piston valve 230 in aleft-hand direction as viewed in FIGURE 9, the movement of the valve 23)uncovers the ports of the passages 236 and 4241) in the bore or cylinder226 so that air from the air inlet region 14 flows through the passage236 into the bore 226 at the right-hand end of the piston valve 230,thence through the passages or channels 246, 242, the restricted airmetering channel 245 and passage 186 to admit air into the acceleratingWell 176, shown in FIGURE 5, for admixing with the fuel dischargedthrough the main orifice 162.

This operating condition obtains when the engine with which thecarburetor may be used is operating under light loads where full poweris not required and thus the fuel and air ratio in the mixing passage isleaned out, viz. the amount of fuel to the volume of air moving throughthe mixing passage is reduced, effecting substantial economy inoperation of the carburetor.

The operation of the charge forming apparatus or carburetor of theinvention may be best understood by additional reference to thesemi-diagrammatic view of FIG- URE 12. The engine is started by aconventional cranking method with the throttle valve 54 in partial orfull open position and the choke valve 28 moved to closed positionthrough the manipulation of the arm 35. When the `manipulating arm 35 isrotated in a direction to close the choke valve 28, the spring in thechamber' 41 of the cylindrical member 34 resiliently urges or biases thechoke valve to closed position.

When the engine has started, air velocity through the mixing passage isincreased and if the operator has not fully returned the arm 35 andmember 34 toward full open position of the choke valve, the air velocityacting against the choke valve 28, which is eccentrically mounted withrespect to the air inlet 14, is opened by the air pressure against thetension of the spring S so that continued engine operation is assuredeven though the manipulating arm 35 and member 34 have not been returnedto fully open the choke valve 28.

Various engine operating conditions and speeds infiuence the action ofvarious components of the carburetor construction and fuel flow throughvarious channels for delivery into the mixing passage 12. Consideringthe operation of the carburetor when the internal cornbustion enginewith which it is used is operating at idling speed, fuel flow to themixing passage is as follows: Under engine idling conditions thethrottle valve 54 is in near closed position, the idling orifice 1911being at the mixture outlet side of the throttle valve, delivers fuelfor engine idling purposes. With the throttle 54 in near closedposition, the pressure in the venturi 15 is substantially atmosphericand hence the check ball Valve 164 is in a position closing the passageor duct 166 in the tubular fitting 160 shown in FIGURE 5.

This action prevents back bleeding of air from the mixing passagethrough the main orifice 162 into the fuel system. The meteringdiaphragm 70 is under the influence of the reduced pressure in themixture outlet 17 through the idling orifice 19t) and the passagescommunieating therewith through the accelerating well 170.

The aspiration or reduced pressure in the outlet region of the mixingpassage elevates the diaphragm 70 as viewed in vFIGURES and 6, swingingthe lever 245 in a counterclockwise direction about its pivot 132, whichmovement effects a lowering of the valve body 142 whereby the valveportion 150 moves away from the annular valve seat' 146 so that fuelfiows from the supply through the port 148 along the facets of the valvebody 142 into the fuel chamber 68. The aspiration effective in thechannel 136 is communicated to the well 170 shown in FIGURE 7 1@ t'ocause fuel iiow into the well 170 through the passage 182, bore 17S andmetering restriction 180.

It should be noted from FIGURE 5 that the channel 186 which conveys fuelaway from the well 170 to the idling and low speed orifices is incommunication with the upper region of the well 170 so that the latteris filled with fuel during engine idling and low speed operation.

If the throttle 54 is opened sufficiently to bring into operation thedelivery of fuel through the low speed orilice 192, fuel flow issubstantially thesame as with idling speed fuel discharge except thatthe fuel is delivered through the secondary system viz. both orifices19t! and 192 with increased fuel flow through the carburetor due to theaspiration effective on both orifices 190 and 192.

As the engine speed is increased by further gradual opening of thethrottle S4, the pressure in the mixing passage rises adjacent theorifices 190 and 192 and decreases in the choke band region 16 of theventuri so that the engine aspiration acts through the main orifice 162to elevate the ball check valve 164 which is formed of nylon or otherlight material and discharge fuel from the well 170 through the passage166 and the main orifice 162 into the mixing passage.

There may be some overlapping of fuel delivery through the secondaryorifices with that of the main orifice 162, but as engine speedincreases the delivery of fuel through the secondary orifices nearlyceases by reason of the high aspiration or reduced pressure in theventuri acting upon the main fuel delivery orifice 162. If the throttle54 is moved toward open position, the fuel in the accelerating well 17@is delivered through the main orifice 162 for engine acceleratingpurposes.

When the engine is operating under idling or low speed conditions, thereduced pressure at the engine side of the throttle 54 is effectivethrough the orifice 104 and passages 106 and 110 to establish reducedpressure in the chamber 87 beneath the second diaphragm S0 to cause thelatter to move or be liexed downwardly as viewed in FIGURE 5,compressing the spring 97.

When the throttle 54 is suddenly moved toward full open or near openposition rapid acceleration is attained in the following manner: Thepotential energy set up in the compressed spring 97 is effective torapidly move the diaphragm S0 upwardly, imparting a momentary pressureimpulse to the metering diaphragm 7i) to cause further opening of thevalve 15@ through the movement of the lever 245 so fuel enters the fuelchamber 68 at an increased rate for delivery into the mixing passagethrough the well 170 and the main orifice 162.

The rapid release of the compression of spring 97 occurs for the reasonthat the reduced pressure which had been effective on the orifice 164and passages 1116 and 116 is rapidly increased when the throttle valveS4 is opened rapidly so that the pressure in the chamber S7 shown inFIGURE 5 is rapidly increased and the second diaphragm moved upwardlyrapidly by the rapid expansion of the spring 97.

It should be noted that the vent opening is of comparatively small sizein cross-sectional area and serves to prevent fuel from the mixingpassage accumulating in the chamber 87.

The metering diaphragm 71) is under the normal influence of aspirationin the mixing passage, the fuel chamber 66 being unvented except throughthe fuel discharge orifices. The pressure in the chambers 75 and 77between the diaphragms is equalized through the restricted passage 12eIand the passage 120 opening into the air inlet region 14 through themedium of the tube 118.

When the engine is operating at intermediate speeds and` undercomparatively light loads Where full power is not required, the fuel andair mixture is leaned out by operation of the automatic means foradmitting additional air to the fuel prior to its discharge through themain nozzle or outlet 162. When the throttle valve is lt in closed ornear closed position, there is insufiicient reduction in pressureeffective on the orifice 254 and associated passages to cause movementof the piston valve 230 from its normal port-closing position shown inFIG- URE 9.

However, when the engine is operating at intermediate speeds under lightloads with the throttle in partial open or intermediate position, thepressure in the'mixing passage at the region of the throttle is reducedand is effective in the bore or cylinder 226 to cause longitudinalmovement of the piston valve 236 in a left-hand direction, as viewed inFIGURES 9 and l2, compressing the spring 232 and establishingcommunication between the passages 236 and 24d through the bore 226 soas to admit air from the air inlet region 1d through passage 236, bore226,V passages 240, 242, the restricted air metering passage 245 and thefuel channel ld into the well E76.

The additional air is mixed with the fue! discharged through the mainorifice 162 so that the ratio of fuel to the air is reduced, thuseffecting economy of operation of the carburetor under such engineoperating conditions.

Under all conditions of operation, a small amount of air is bled intothe fuel from the air inlet region 14 through the minute air bleedpassage 22) in the cuplike fitting 218, shown in FIGURES and l2, so thatan emulsion of fuel and air is delivered through the main orifice 262and some air bled into the fuel delivered through the secondary systemcomprising the orifices 190 and 192 for engine idling and low speedoperation.

Whenever the load on the engine increases and the throttle 5d openedfully or to near open position to take care of increased load on theengine or to rapidly increase the speed of the engine, the pressure inthe mixing passage adjacent the orifice 254, shown in FIGURE 9 isincreased, and the potential energy of the compressed spring 232 isreleased to move the piston valve 230 to its port-closing position, asshown in FIGURES 9 and l2 to interrupt or cut olic the supply ofadditional air to the channel 186 so that the fuel flow through the mainorice 162 is increased and a richer mixture or a greater amount of fuelper unit of air is established in the mixing passage to take care of theadded power requirements.

The fuel flow to the idling and low speed orifices 199 and 92 iscontrolled or metered by manual adjustment' of the metering valve 26dshown in FlGURE 8.

The carburetor of the invention is adaptable for both small and largeengines of both two and four cycle types and is especially adaptable forfour cycle engines where effective accelerating characteristics arerequired and yet economies in fuel consumption effected under light loadconditions through the automatic control of fuel and' air ratio Iby theadmission of additional air bled into the fuel prior to its dischargefrom the main orifice 162.

While a fixed fuel metering restriction 180, as shown in FIGURE 7, isutilized for controlling or metering fuel flow to the fuel deliverysystem, it is to be understoodv that an adjustable needle valve of thecharacter illustrated at 2.36 in FIGURE 8 may lbe employed in lieu ofthe fixed fuel metering passage ist! shown in FIG- URE 7.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than as herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

I claim:

lQCharge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, adiaphragmvforming with said recess a fuel chamber, a throttle valve forthe mixing passage, means controlled by said diaphragm for admittingliquid fuel from a supply into the chamber, orifice means for deliveringfuel into the mixing passage, fuel conveying duct means in communicationwith the chamber and the orifice means wherebyV fuel is delivered intothe mixing passage by differential pressures in the mixing passage,passage means arranged to admit air into the duct means for adrnixingwith the liquid fuel delivered through the orifice means, and valvemeans cooperating with said air passage means and movable bydifferential pressure in the mixing passage for controlling theadmission of air through said passage means into said duct means.

2. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm extending across the recess and forming therewith a fuelchamber, a fuel inlet in said body member, a valve for said inletcontrolled by said diaphragm for admitting liquid fuel from a supplyinto the chamber, a throttle valve for the mixing passa e, an orificefor delivering fuel into the mixing passage, lfuel conveying duct meansin communication with the chamber and the orifice whereby fuel isdelivered into the mixing passage by aspiration in said mixing passage,air passage means arranged to admit air into the duct means for admixingwith the liquid fuel delivered through the orifice, relatively movablevalve means disposed in said air passage means, said valve means beingarranged to be moved by pressure differentials in the mixing passage forcontrolling the admission of air into said duct means.

3. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm forming with said recess a fuel chamber, a throttle valve forthe mixing passage, a fuel inlet in said'body member, a valve for saidinlet controlled by said diaphragm for admitting fuel from a supply intothe chamber, orifice means for delivering fuel from the chamber into themixing passage, fuel conveying duct means in communication with thechamber and the orifice means where'oy fuel is delivered into the mixingpassage by aspiration in said mixing passage, air channel means arrangedto admit air into the duct means for admixing with the liquid fueldelivered through the orifice means, an air chamber in Communicationwith said air channel means, valve means movable in said air chamber,resiiient means normally biasing the valve means to a positioninterrupting air fiow through the air channel means, said valve meansbeing arranged to be moved by reduced pressure in the mixing passage toa position admitting air through the air channel means into said ductmeans.

4. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm forming with said recess a fuel chamber, a throttle valve forthe mixing passage, means controlled by said diaphragm for admittingfuel from a supply into the chamber, orifice means for delivering fuelinto the mixing passage, fuel conveying duct means in communication withthe chamber and the orifice means whereby fuel is delivered into themixing passage by differential pressures in said mixing passage, airchannel means arranged to admit air into the duct meansV for admixingwith the liquid fuel delivered through the orifice, an air chamber incommunication with said air channel means and the mixing passage, andvalve means in said air chamber reciprocable under the infiuence ofvarying pressures in the mixing passage for controlling air fiow throughsaid air channel means, and a restriction in said air channel means formetering air fiow therethrough.

5. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess a fuel chamber, a throttle valve for the mixingpassage, means controlled by said diaphragm for admitting fuel from asupply into the chamber, orifice means for delivering fuel into themixing passage, fuel conveying'duct means in communication with thechamber and 13 the orifice means whereby fuel is delivered into themixing passage by dierential pressures in said mixing passage, airpassage means formed in said body including a port in communication withsaid fuel duct means, and movable valve means cooperating with said portactuated by variation in pressure in the mixing passage for controllingair tlow through said air passage means.

6. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm forming with said recess a fuel chamber, a throttle valve forthe mixing passage, said body member being formed with a fuel inlet,means cooperating With the inlet controlled by said diaphragm foradmitting liquid fuel from a supply into the chamber, orifice means fordelivering fuel into the mixing passage, fuel conveying duct means incommunication with the chamber and the orifice means whereby fuel isdelivered into the mixing passage by differential pressures in saidmixing passage, an air chamber formed in said body, valve means movablein said chamber, an air inlet for the air chamber, air passage meansbetween said air chamber and said fuel duct means, a channelestablishing communication between the air chamber and the mixingpassage, and means normally biasing the valve means to a positioninterrupting air ow through said air passage means, said valve meansbeing adapted to be moved under the iniiuence of reduced pressure insaid mixing passage communicated to the air chamber through saidchannel.

` 7. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess a fuel chamber, a throttle valve for the inletpassage, inlet valve means controlled by said diaphragm for admittingliquid fuel from a supply in the chamber, primary and secondary orificesfor delivering fuel into the mixing passage, fuel conveying duct meansin communication with the chamber and the orices whereby fuel isdelivered into the mixing passage by differential pressures in saidmixing passage, air passage means in communication with said fuel ductmeans, and valve means movable under the influence of reduced pressurein said mixing passage for controlling air flow through said air passagemeans to the duct means for admixing with liquid fuel delivered throughthe primary oriice into the mixing passage.

8. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm forming with said recess a fuel chamber, a throttle valve forthe mixing passage, means controlled by said diaphragm for admittingliquid fuel from a supply into the chamber, an orifice for deliveringfuel into the mixing passage, fuel conveying duct means in communicationwith the chamber and the orifice whereby fuel is delivered into themixing passage by differential pressures in said mixing passage, an airchamber formed in said body, valve means movable in said chamber,an airinlet for the air chamber, air passage means between said air chamberand said fuel duct means, a channel establishing communication betweenthe air chamber and the mixing passage, resilient means normally biasingthe valve means to a position interrupting air ow through said airpassage means, said valve means being adapted to be moved under theinfluence of reduced pressure in said mixing passage communicated to theair chamber through said channel, and a restriction in said air passagefor metering air admitted to the fuel duct means.

9. Charge forming apparatus including, in combination, a body memberformedwith a fuel and air mixing passage and a recess, a diaphragmforming with said recess an unvented fuel chamber, a throttle Valve inthe mixing passage, a fuel inlet formed in said body in communicationwith the chamber, means in said inlet actuated by said diaphragm forcontrolling ow of liquid fuel from a supply into said chamber, a mainfuel delivery system including a fuel well formed in said member fordelivering fuel from the chamber into the mixing passage, a secondaryfuel delivery system for delivering fuel to the mixing passage, saidsecondary fuel delivery system being in communication with the well by afuel conveying duct whereby fuel iiow through the secondary systemeffects delivery of fuel from the chamber into the Well, said bodymember being formed with air channel means in communication with thefuel duct for admitting air into the well for admixing with fueldelivered by the main fuel delivery system into the mixing passage, andvalve means actuated by varying pressures in the mixing passage forcontrolling air flow through said air channel means.

10. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a shallow recess, adiaphragm forming with said recess an unvented fuel chamber, a throttlevalve in the mixing passage, a fuel inlet formed in said body incommunication with the chamber, means in said inlet actuated by saiddiaphragm for controlling liquid fuel from a supply into said chamber, amain fuel delivery system including a fuel well formed in said memberfor delivering fuel from the chamber into the mixing passage, asecondary fuel delivery system for delivering fuel to the mixingpassage, said secondary fuel delivery system being in communication withthe well and arranged whereby fuel iiow through the secondary systemeffects delivery of fuel from the fuel chamber into the well, said bodymember being formed with an air chamber, a valve for said air chamber,air passage means between the air chamber and the fuel well, a channelconnecting the air chamber with the outlet region 0f the mixing passage,said valve being under the influence of pressure variations in themixing passage for actuating the Valve to control the admission of airthrough said air passage means into the fuel well.

ll. Charge forming apparatus inclding, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess an unvented fuel chamber, a throttle valve inthe mixing passage, a fuel inlet formed in said body in communicationwith the chamber, means in said inlet actuated by said diaphragm forcontrolling liquid fuel from a supply into said fuel chamber, a mainfuel delivery system including a fuel well formed in said member fordelivering fuel from the chamber into the mixing passage, a secondaryfuel delivery system for delivering fuel to the mixing passage, saidsecondary fuel delivery system being in communication with the well andarranged whereby fuel flow through the secondary system effects deliveryof fuel from the chamber into the well, said body member having acylinder formed therein, a valve movable in said cylinder, a channelbetween the cylinder and an air inlet region of the mixing passage, asecond channel between the cylinder and the main fuel delivery system, athird channel between the cylinder and the outlet region of the mixingpassage, means normally biasing the valve toward a position cl-osing thesecond channel, said valve being under the iniiuence of pressurevariations in the mixing passage for actuating the valve to control theadmission of air through said first and second lchannels into the mainfuel delivery system.

l2. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess a fuel chamber, a throttle valve for the mixingpassage, means controlled by said diaphragm for admitting liquid fuelfrom a supply into the fuel chamber, orifice means for delivering fuelinto the mixing passage, fuel conveying duct means in communication withthe fuel chamber and the orice means whereby fuel is aspirated into themixing passage by differential pressures in said mixing passage, an aircontrol valve in the inlet region of the mixing passage, a shaftjournaled in the body memaccese? ber and supporting said air controlvalve, the axis of the shaft being transverse to and at one side of theaxis of the mixing passage, an element journaled for rotation relativeto said shaft, cooperating means on said shaft and element wherebymovement of the element in one direction effects movement of the shaftand air control valve in the same direction, and resilient meansengaging the shaft and element whereby differential pressure acting onsaid air control valve opens said valve.

13. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess a fuel chamber, a throttle valve in the mixingpassage, means controlled by said diaphragm for admitting liquid fuelfrom a supply into the chamber, orice means for delivering fuel into themixing passage, fuel conveying duct means in communication with thechamber and orifice means whereby fuel is delivered into the mixingpassage by differential pressures in said mixing passage, an air controlvalve in the inlet region of the mixing passage, a shaft journaled inthe body member and supporting said air control valve, the axis of theshaft being transverse to and at one side of the axis of the mixingpassage, an element journaled for rotation relative to said shaft,cooperating abutment means 4on said shaft and element whereby movementof the element in one direction eects movement of the shaft and aircontrol valve in the same direction, a member mounted by said element,and resilient means connecting the shaft and member whereby differentialpressure acting on Said air control valve opens said valve, said memberbeing adjustable relative to said element for varying the effectiveforce of said resilient means.

14. Charge forming apparatus including, in combination, a body memberformed with a fuel and air mixing passage and a recess, a diaphragmforming with said recess a fuel chamber, a throttle valve in said mixingpassage, means controlled by said diaphragm for admitting liquid fuelfrom a supply into the chamber, orifice means for delivering fuel intothe mixing passage, fuel conveying duct means in communication with thechamber and `orifice means whereby fuel is delivered into the mixingpassage by differential pressures in said mixing passage, air passagemeans arranged to admit air into the duct means for admixing with theliquid fuel delivered through the orifice means, means associated withsaid air passage means and influenced by pressure differentials in themixing passage for controlling the admission of air into said ductmeans, an air control valve in the inlet region of the mixing passage, ashaft journaled in the body member and supporting said air controlvalve, the axis of the shaft being transverse to and at one side of theaxis of the mixing passage, an element journaled for rotation relativeto said shaft, cooperating abutment means on said shaft and elementwhereby movement of the element in one direction effects movement of theshaft and air control valve in the same direction, and resilient meansarranged between the shaft and element whereby differential pressureacting on said air control valve opens said valve.

l5. Charge forming apparatus in combination, a body member formed with amixing passage and a recess, a flexible diaphragm extending across saidrecess and forming therewith a fuel chamber, said body being formed witha fuel inlet, means actuated by movement of the diaphragm forcontrolling flow of liquid fuel from a supply into the fuel chamber,main and secondary fuel orifices for delivering fuel from the fuelchamber into the mixing passage, duct means connecting the main andsecondary orifices with the fuel chamber, a throttle valve in themixture outlet region of the mixing passage, an air control valve in theinlet region of the mixing passage, a shaft journaled in the body memberand supporting said air control valve, the axis of the shaft beingtransverse to the axis of the mixing passage and at one side of themixing passage axis, an element journaled for rotation relative to saidshaft, cooperating abutment means of said shaft and element wherebymovement of the element in one direction effects movement of the shaftand air control valve in the same direction, and resilient means havingoperative connection with the shaft and element whereby differentialpressure acting on said air control valve opens said valve.

Phillips June 25, 1957 Brown Feb. 18, 1958

